Diagnostic system for a vehicle electrical system

ABSTRACT

A diagnostic having an analog-to-digital converter that is electrically coupled to an output port of a first analog multiplexer and an output port of a second analog multiplexer is provided. The analog-to-digital converter receives the high side voltage level signal and the low side current level signal at first and second times, respectively, and outputs a high side voltage value and a low side current value, respectively, based on the high side voltage level signal and the low side current level signal, respectively, that are received by a microcontroller. The microcontroller commands a high side driver circuit and a low side driver circuit to transition a contact of the contactor to an open operational position when the first analog multiplexer is malfunctioning based on the high side voltage value.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/500,816 filed on May 3, 2017, the entire contents of which arehereby incorporated by reference herein.

BACKGROUND

The inventors herein have recognized a need for an improved diagnosticsystem for a vehicle electrical system that utilizes first and secondanalog multiplexers. The diagnostic system transitions a contactor to anopen operational position if at least one of the first and second analogmultiplexers are malfunctioning.

SUMMARY

A diagnostic system for a vehicle electrical system in accordance withan exemplary embodiment is provided. The vehicle electrical system has abattery module, a contactor, a high side driver circuit, and a low sidedriver circuit. The diagnostic system includes a high side voltagemeasuring circuit that is electrically coupled to the high side drivercircuit and to a first input port of a first analog multiplexer. Thehigh side voltage measuring circuit generates a high side voltage levelsignal corresponding to a high side voltage being applied to a contactorcoil of the contactor. The high side voltage level signal is received bythe first input port. The diagnostic system further includes a low sidecurrent measuring circuit that is electrically coupled to the low sidedriver circuit, and is further electrically coupled to a second inputport of a second analog multiplexer. The low side current measuringcircuit generates a low side current level signal corresponding to anamount of electrical current flowing through the contactor coil that isreceived by the second input port. The diagnostic system furtherincludes an analog-to-digital converter that is electrically coupled toan output port of the first analog multiplexer and an output port of thesecond analog multiplexer. The analog-to-digital converter receives thehigh side voltage level signal and the low side current level signal atfirst and second times, respectively, and outputs a high side voltagevalue and a low side current value, respectively, based on the high sidevoltage level signal and the low side current level signal,respectively, that are received by a microcontroller. Themicrocontroller commands the high side driver circuit and the low sidedriver circuit to transition a contact of the contactor to an openoperational position when the first analog multiplexer is malfunctioningbased on the high side voltage value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are schematics of a vehicle having a vehicle electricalsystem and a diagnostic system in accordance with an exemplaryembodiment; and

FIGS. 2-5 is a flowchart of a diagnostic method utilized by thediagnostic system of FIGS. 1A and 1B.

DETAILED DESCRIPTION

Referring to FIGS. 1A and 1B, a vehicle 10 is provided. The vehicle 10includes a vehicle electrical system 30, and a diagnostic system 40 inaccordance with an exemplary embodiment.

The vehicle electrical system 30 includes a battery module 60, acontactor 70, a high side driver circuit 80, a low side driver circuit82, electrical lines 100, 102, 104, 106, 107, 108, a voltage regulator110, and a voltage regulator 112.

An advantage of the diagnostic system 40 is that the system 40transitions the contactor 70 to an open operational position if at leastone of the first and second analog multiplexers 301, 302 aremalfunctioning.

For purposes of understanding, a node is a region or a location in anelectrical circuit.

The term “substantially” means ±5% of a value herein.

The battery module 60 includes a positive terminal 180 and a negativeterminal 182. In an exemplary embodiment, the battery module 60generates substantially 48 Vdc between the positive terminal 180 and thenegative terminal 182. The positive terminal 180 is electrically coupledto a node 234 of the contactor 70. The negative terminal 182 iselectrically coupled to electrical ground.

The contactor 70 has a contact 230, a contactor coil 232, a first node234, and a second node 236. The first node 234 is electrically coupledto the positive terminal 180 of the battery module 60 utilizing theelectrical line 100. The second node 236 is electrically coupled to theelectrical load 90 utilizing the electrical line 106. When themicrocontroller 314 generates first and second control signals that arereceived by the high side driver circuit 80 and the low side drivercircuit 82, respectively, the contactor coil 232 is energized whichtransitions the contact 230 to a closed operational state. Alternately,when the microcontroller 314 generates third and fourth control signalsthat are received by the high side driver circuit 80 and the low sidedriver circuit 82, respectively, the contactor coil 232 is de-energizedwhich transitions the contact 230 to an open operational state. In anexemplary embodiment, the third and fourth control signals can each be aground voltage level.

The high side driver circuit 80 and the low side driver circuit 82 areprovided to energize or de-energize the contactor coil 232. The highside driver circuit 80 is electrically coupled to the microcontroller314 utilizing the electrical line 107. The high side driver circuit 80is further electrically coupled to a first end of the contactor coil 232utilizing the electrical line 102. The high side driver circuit 80energizes the contactor coil 232, when the high side driver circuit 80receives a control signal from the microcontroller 314.

The low side driver circuit 82 is electrically coupled to themicrocontroller 314 utilizing the electrical line 108. The low sidedriver circuit 82 is further electrically coupled to a second end of thecontactor coil 232 utilizing the electrical line 104. The low sidedriver circuit 82 is configured to conduct an electrical currenttherethrough to the electrical ground for energizing the contactor coil232, when the low side driver circuit 82 receives a control signal fromthe microcontroller 314.

The electrical load 90 is electrically coupled to the second node 236 ofthe contactor 70. When the contactor 70 has a closed operationalposition, a positive voltage from the battery module 60 is applied tothe electrical load 90 for energizing the electrical load 90. When thecontactor 70 has an open operational position, the positive voltage fromthe battery module 60 is removed from the electrical load 90 whichde-energizes the electrical load 90.

The voltage regulator 110 has an output terminal that outputs a firstvoltage (e.g., substantially 3.3 Vdc) therefrom. The output terminal ofthe voltage regulator 110 is electrically coupled to the input portIN1_2 of the second analog multiplexer 302, and to the voltage dividercircuit 286, and to the voltage clamping circuit 282, which each receivethe first voltage from the output terminal of the voltage regulator 110.The output terminal of the voltage regulator 110 is further electricallycoupled to the microcontroller 314.

The voltage regulator 112 has an output terminal that outputs a secondvoltage (e.g., substantially 5.0 Vdc) therefrom. The output terminal ofthe voltage regulator 112 is electrically coupled to the input portIN3_1 of the first analog multiplexer 301, and to the voltage dividercircuit 294, and to the voltage diver circuit 298, which each receivethe second voltage from the output terminal of the voltage regulator112.

The diagnostic system 40 includes a high side voltage measuring circuit270, a low side current measuring circuit 274, a voltage clampingcircuit 282, a voltage divider circuit 286, a voltage divider circuit294, a voltage divider circuit 298, a first analog multiplexer 301, asecond analog multiplexer 302, a multiplexer selection device 306, ananalog-to-digital converter 310, and a microcontroller 314.

The high side voltage measuring circuit 270 is electrically coupled tothe high side driver circuit 80 and to the input port IN1_1 of the firstanalog multiplexer 301. The high side voltage measuring circuit 270generates a high side voltage level signal (HS_VOLTAGE) corresponding toa high side voltage being applied to the contactor coil 232 of thecontactor 70. The high side voltage level signal (HS_VOLTAGE) isreceived by the input port IN1_1 of the first analog multiplexer 301.

The low side current measuring circuit 274 is electrically coupled tothe low side driver circuit 82, and is further electrically coupled toan input port IN2_2 of the second analog multiplexer 302. The low sidecurrent measuring circuit 274 generates a low side current level signal(LS_CURRENT) corresponding to an amount of electrical current flowingthrough the contactor coil 232 that is received by the input port IN2_2of the second analog multiplexer 302.

The voltage clamping circuit 282 is electrically coupled to the voltageregulator 110, and is further electrically coupled to the input portIN2_1 of the first analog multiplexer 301. The voltage clamping circuit282 receives the voltage (REG_3.3) from the voltage regular 110, andoutputs a voltage (CLAMP_3.3) in response thereto that is received atthe input port IN2_1 of the first analog multiplexer 301.

The voltage divider circuit 286 is electrically coupled to the voltageregulator 110, and is further electrically coupled to the input portIN3_2 of the second analog multiplexer 302. The voltage divider circuit286 receives the voltage (REG_3.3) from the voltage regular 110, andoutputs a voltage (VD_3.3) in response thereto that is received at theinput port IN3_2 of the second analog multiplexer 302. The voltage(VD_3.3) is less than the voltage (REG_3.3).

The voltage divider circuit 294 is electrically coupled to the voltageregulator 112, and is further electrically coupled to the input portIN4_1 of the first analog multiplexer 301. The voltage divider circuit294 receives the voltage (REG_5.0) from the voltage regular 112, andoutputs a voltage (VD_5.0_1) in response thereto that is received at theinput port IN4_1 of the first analog multiplexer 301. The voltage(VD_5.0_1) is less than the voltage (REG_5.0).

The voltage divider circuit 298 is electrically coupled to the voltageregulator 112, and is further electrically coupled to the input portIN4_2 of the second analog multiplexer 302. The voltage divider circuit294 receives the voltage (REG_5.0) from the voltage regular 112, andoutputs a voltage (VD_5.0_2) in response thereto that is received at theinput port IN4_2 of the second analog multiplexer 302. The voltage(VD_5.0_2) is less than the voltage (REG_5.0).

The first analog multiplexer 301 is provided to selectively route onesignal from one of the input ports IN1_1, IN2_1, IN3_1, IN4_1 to theoutput port OUT_1. The first analog multiplexer 301 has the input portsIN1_1, IN2_1, IN3_1, IN4_1, the output port OUT_1, a select port SEL_1,and address ports A0_1, A1_1, A2_1. The input port IN1_1 is electricallycoupled to the high side voltage measuring circuit 270. The input portIN2_1 is electrically coupled to the voltage clamping circuit 282. Theinput port IN3_1 is electrically coupled to the voltage regulator 112.The input port IN4_1 is electrically coupled to the voltage dividercircuit 294. The output port OUT_1 is electrically coupled to the inputport AD_IN of the analog-to-digital converter 310. The address portsA0_1, A1_1, A2_1 are electrically coupled to the address ports A0, A1,A2, respectively, of the multiplexer selection device 306. The selectport SEL_1 is electrically coupled to the select port SEL_1 of themultiplexer selection device 306.

When the multiplexer selection device 306 outputs a high logic levelthat is received at the select port SEL_, the first analog multiplexer301 is selected. Further, the multiplexer selection device 306 outputsthe address signals A0, A1, A2 that is received at the address portsA0_1, A1_1, A2_1, respectively, to select one of the input ports IN1_1,IN2_1, IN3_1, IN4_1 in which to route an associated analog signalthereof to the output port OUT_1. For example, when the first analogmultiplexer 301 and the input port IN1_1 is selected, the signal(HS_VOLTAGE) is routed from the input port IN1_1 to the output portOUT_1 and is further routed to the analog-to-digital converter 310.Further, the analog-to-digital converter 310 measures the signal(HS_VOLTAGE) and generates an associated voltage value that is receivedby the microcontroller 314.

The second analog multiplexer 302 is provided to selectively route onesignal from one of the input ports IN1_2, IN2_2, IN3_2, IN4_2 to theoutput port OUT_2. The second analog multiplexer 302 has the input portsIN1_2, IN2_2, IN3_2, IN4_2, the output port OUT_2, a select port SEL_2,and address ports A0_2, A1_2, A2_2. The input port IN1_2 is electricallycoupled to the voltage regulator 110. The input port IN2_2 iselectrically coupled to the low side current measuring circuit 274. Theinput port IN3_2 is electrically coupled to the voltage divider circuit286. The input port IN4_2 is electrically coupled to the voltage dividercircuit 298. The output port OUT_2 is electrically coupled to the inputport AD_IN of the analog-to-digital converter 310. The address portsA0_2, A1_2, A2_2 are electrically coupled to the address ports A0, A1,A2, respectively of the multiplexer selection device 306. The selectport SEL_2 is electrically coupled to the select port SEL_1 of themultiplexer selection device 306.

When the multiplexer selection device 306 outputs a high logic levelthat is received at the select port SEL_2, the second analog multiplexer302 is selected. Further, the multiplexer selection device 306 outputsthe address signals A0, A1, A2 that is received at the address portsA0_2, A1_2, A2_2, respectively, to select one of the input ports IN1_2,IN2_2, IN3_2, IN4_2 in which to route an associated analog signalthereof to the output port OUT_2. For example, when the second analogmultiplexer 302 and the input port IN1_2 is selected, the signal(REG_3.3) is routed from the input port IN1_2 to the output port OUT_2and is further routed to the analog-to-digital converter 310. Further,the analog-to-digital converter 310 measures the signal (REG_3.3) andgenerates an associated voltage value that is received by themicrocontroller 314.

The multiplexer selection device 306 is provided to select one of thefirst and second analog multiplexers 301, 302 at a time for routing asignal to the analog-to-digital converter 310, in response to a controlsignal from the microcontroller 314. The multiplexer selection device306 includes a control port CT, a select port SEL_1, a selection portSEL_2, and address ports A0, A1, A2. The control port CT is electricallycoupled to the microcontroller 314. The selection port SEL_1 iselectrically coupled to the select port SEL_1 of the first analogmultiplexer 301. The selection port SEL_2 is electrically coupled to theselect port SEL_2 of the second analog multiplexer 302. The addressports A0, A1, A2 are electrically coupled to the address ports A0_1,A1_1, A2_1, respectively, of the first analog multiplexer 301 and toaddress ports A0_2, A1_2, A2_2, respectively, of the second analogmultiplexer 302.

When the multiplexer selection device 306 receives a control signal fromat the control port CT indicating a specific analog multiplexer toselect and a specific port within the analog multiplexer to select, themultiplexer selection device 306 generates a high logic level at one ofthe select ports SEL_1, SEL_2, and corresponding signals in the addressports A0, A1, A2.

The analog-to-digital converter 310 has an input port AD_IN and anoutput port AD_OUT. The input port AD_IN is electrically coupled to anoutput port OUT_1 of the first analog multiplexer 301 and an output portOUT_2 of the second analog multiplexer 302. The output port AD_OUT iselectrically coupled to the microcontroller 314. The analog-to-digitalconverter 310 measures a signal at the AD_IN input port and generates avalue corresponding to a magnitude of the signal at the AD_IN input portthat is output at the output port AD_OUT and is received by themicrocontroller 314. In an exemplary embodiment, the analog-to-digitalconverter 310 is a single channel analog-to-digital converter.

The microcontroller 314 is programmed to monitor voltages utilizing themicroprocessor 400 which executes software instructions stored in thememory device 402. The microprocessor 400 is operably coupled to thememory device 402, the analog-to-digital converter 310, the multiplexerselection device 306, the high side driver circuit 80, the low sidedriver circuit 82, and the voltage regulator 110. The microcontroller314 outputs control signals that are received by the driver circuits 80,82 for controlling the operation of the contactor 70. The memory device402 stores data, tables, and the software applications described hereinfor implementing the methods described therein.

Referring to FIGS. 1A, 1B, and 2-5, a flowchart of a diagnostic methodfor the vehicle electrical system 30 will now be explained.

At step 500, the microcontroller 314 commands a high side driver circuit80 and a low side driver circuit 82 to energize a contactor coil 232 totransition a contact 230 of a contactor 70 to a closed operationalposition. After step 500, the method advances to step 502.

At step 502, the high side voltage measuring circuit generates a highside voltage level signal corresponding to a high side voltage beingapplied to the contactor coil 232. The high side voltage level signal isreceived by a first input port (e.g., input port IN1_1) of a firstanalog multiplexer 301. After step 502, the method advances to step 504.

At step 504, the microcontroller 314 commands a multiplexer selectiondevice 306 to select the first analog multiplexer 301 and the firstinput port (e.g., input port IN1_1) thereof at a first time such that ananalog-to-digital converter 310 receives the high side voltage levelsignal from the output port AD_OUT of the first analog multiplexer 301at a first time. After step 504, the method advances to step 506.

At step 506, the analog-to-digital converter 310 outputs a high sidevoltage value based on the high side voltage level signal that isreceived by a microcontroller 314. After step 506, the method advancesto step 508.

At step 508, the low side current measuring circuit 274 generates a lowside current level signal corresponding to an amount of electricalcurrent flowing through the contactor coil 232 that is received by afirst input port (e.g., input port IN2_2) of a second analog multiplexer302. After step 508, the method advances to step 510.

At step 510, the microcontroller 314 commands the multiplexer selectiondevice 306 to select the second analog multiplexer 302 and the firstinput port (e.g., input port IN2_2) thereof at a second time such thatan analog-to-digital converter 310 receives the low side current levelsignal from the output port OUT_2 of the second analog multiplexer 302at a second time. After step 510, the method advances to step 512.

At step 512, the analog-to-digital converter 310 outputs a low sidecurrent value on the low side current level signal that is received bythe microcontroller 314. After step 512, the method advances to step514.

At step 514, the microcontroller 314 makes a determination as to whetherthe high side voltage value is not within a first desired voltage valuerange when the first analog multiplexer 301 is selected by themicrocontroller 314 indicating that the first analog multiplexer 301 ismalfunctioning. If the value of step 514 equals “yes”, the methodadvances to step 516. Otherwise, the method advances to step 520.

At step 516, the microcontroller 314 commands the high side drivercircuit 80 and the low side driver circuit 82 to de-energize thecontactor coil 232 to transition the contact 230 of the contactor 70 toan open operational position. After step 516, the method advances tostep 518.

At step 518, the microcontroller 314 determines that the contact 230 ofthe contactor 70 has the open operational position, when the low sidecurrent value is within a first predetermined current value range. Afterstep 518, the method advances to step 520.

At step 520, the microcontroller 314 makes a determination as to whetherthe low side current value is not within a first desired current valuerange when the second analog multiplexer 302 is selected by themicrocontroller 314 indicating that the second analog multiplexer 302 ismalfunctioning. If the value of step 520 equals “yes”, the methodadvances to step 522. Otherwise, the method advances to step 526.

At step 522, the microcontroller 314 commands the high side drivercircuit 80 and the low side driver circuit 82 to de-energize thecontactor coil 232 to transition the contact 230 of the contactor 70 tothe open operational position. After step 522, the method advances tostep 524.

At step 524, the microcontroller 314 determines that the contact 230 ofthe contactor 70 has the open operational position when the high sidevoltage value is within the first predetermined voltage value range.After step 524, the method advances to step 526.

At step 526, the voltage regulator 112 outputs a first voltage. Afterstep 526, the method advances to step 528.

At step 528, the voltage regulator 110 outputs a second voltage. Afterstep 528, the method advances to step 530.

At step 530, the voltage divider circuit 294 outputs a third voltage inresponse to the first voltage from the voltage regulator 112 which isless than the first voltage. The third voltage is received by a secondinput port (e.g., input port IN4_1) of the first analog multiplexer 301.After step 530, the method advances to step 532.

At step 532, the microcontroller 314 commands the multiplexer selectiondevice 306 to select the first analog multiplexer 301 and the secondinput port (e.g., input port IN4_1) thereof at a third time such thatthe analog-to-digital converter 310 receives the third voltage from theoutput port OUT_1 of the first analog multiplexer 301 at the third time.After step 532, the method advances to step 534.

At step 534, the analog-to-digital converter 310 outputs a first voltagevalue based on the third voltage that is received by the microcontroller314. After step 534, the method advances to step 536.

At step 536, the voltage divider circuit 286 outputs a fourth voltage inresponse to the second voltage from the voltage regulator 110 which isless than the second voltage. The fourth voltage is received by a secondinput port (e.g., input port IN3_2) of the second analog multiplexer302. After step 536, the method advances to step 540.

At step 540, the microcontroller 314 commands the multiplexer selectiondevice 306 to select the second analog multiplexer 302 and the secondinput port (e.g., input port IN3_2) thereof at a fourth time such thatthe analog-to-digital converter 310 receives the fourth voltage from theoutput port of the second analog multiplexer 302 at the fourth time.After step 540, the method advances to step 542.

At step 542, the analog-to-digital converter 310 outputs a secondvoltage value based on the fourth voltage that is received by themicrocontroller 314. After step 542, the method advances to step 544.

At step 544, the microcontroller 314 determines a first ratio valueutilizing the following equation: first ratio value=first voltagevalue/second voltage value. After step 544, the method advances to step546.

At step 546, the microcontroller 314 makes a determination as to whetherthe first ratio value is outside of a predetermined ratio rangeindicating that at least one of the first and second analog multiplexer301, 302 are malfunctioning. In particular, the predetermined ratiorange has an upper threshold ratio and a lower threshold ratio, and whenthe first ratio value is less than the lower threshold ratio then themicrocontroller 314 determines that the second analog multiplexer 302 ismalfunctioning, and when the first ratio is greater than the upperthreshold ratio then the microcontroller 314 determines that the firstanalog multiplexer 301 is malfunctioning. If the value of step 546equals “yes”, the method advances to step 548. Otherwise, the method isexited.

At step 548, the microcontroller 314 commands the high side drivercircuit 80 and the low side driver circuit 82 to transition the contact230 of the contactor 70 to the open operational position. After step548, method is exited.

The diagnostic system described herein for a vehicle electrical systemprovides a substantial advantage over other systems. In particular, thediagnostic system described herein transitions a contactor to an openoperational position if at least one of the first and second analogmultiplexers are malfunctioning.

While the claimed invention has been described in detail in connectionwith only a limited number of embodiments, it should be readilyunderstood that the invention is not limited to such disclosedembodiments. Rather, the claimed invention can be modified toincorporate any number of variations, alterations, substitutions orequivalent arrangements not heretofore described, but which arecommensurate with the spirit and scope of the invention. Additionally,while various embodiments of the claimed invention have been described,it is to be understood that aspects of the invention may include onlysome of the described embodiments. Accordingly, the claimed invention isnot to be seen as limited by the foregoing description.

What is claimed is:
 1. A diagnostic system for a vehicle electricalsystem, the vehicle electrical system having a battery module, acontactor, a high side driver circuit, and a low side driver circuit,comprising: a high side voltage measuring circuit being electricallycoupled to the high side driver circuit and to a first input port of afirst analog multiplexer; the high side voltage measuring circuitgenerating a high side voltage level signal corresponding to a high sidevoltage being applied to a contactor coil of the contactor, the highside voltage level signal being received by the first input port; a lowside current measuring circuit being electrically coupled to the lowside driver circuit, and further electrically coupled to a second inputport of a second analog multiplexer; the low side current measuringcircuit generating a low side current level signal corresponding to anamount of electrical current flowing through the contactor coil that isreceived by the second input port; an analog-to-digital converter beingelectrically coupled to an output port of the first analog multiplexerand an output port of the second analog multiplexer, theanalog-to-digital converter receiving the high side voltage level signaland the low side current level signal at first and second times,respectively, and outputs a high side voltage value and a low sidecurrent value, respectively, based on the high side voltage level signaland the low side current level signal, respectively, that are receivedby a microcontroller; and the microcontroller commanding the high sidedriver circuit and the low side driver circuit to transition a contactof the contactor to an open operational position when the first analogmultiplexer is malfunctioning based on the high side voltage value. 2.The diagnostic system of claim 1, wherein the microcontroller furtherdetermining that the contact of the contactor has the open operationalposition based on the low side current value.
 3. The diagnostic systemof claim 1, wherein the microcontroller determines that the first analogmultiplexer is malfunctioning when the analog-to-digital converter isnot outputting the high side voltage value that is within a firstdesired voltage value range when the first analog multiplexer isselected by the microcontroller.
 4. The diagnostic system of claim 1,wherein the microcontroller determines that the contact of the contactorhas the open operational position, when the low side current value iswithin a first predetermined current value range.
 5. The diagnosticsystem of claim 1, further comprising: the microcontroller commandingthe high side driver circuit and the low side driver circuit totransition the contact of the contactor to the open operational positionwhen the microcontroller determines that the second analog multiplexeris malfunctioning based on the low side current value; and themicrocontroller further determining that the contact of the contactorhas the open operational position based on the high side voltage value.6. The diagnostic system of claim 5, wherein the microcontrollerdetermines that the second analog multiplexer is malfunctioning when theanalog-to-digital converter is not outputting the low side current valuethat is within a first desired current value range when the secondanalog multiplexer is selected by the microcontroller.
 7. The diagnosticsystem of claim 5, wherein the microcontroller determines that thecontact of the contactor has the open operational position based on thehigh side voltage value, when the high side voltage value is within afirst predetermined voltage value range.
 8. The diagnostic system ofclaim 1, wherein the microcontroller commanding the high side drivercircuit and the low side driver circuit to transition the contact of thecontactor to the open operational position by stopping a generation offirst and second command signals, respectively, that are received by thehigh side driver circuit and the low side driver circuit, respectively.9. The diagnostic system of claim 1, wherein the analog-to-digitalconverter is a single-channel analog-to-digital converter.
 10. Thediagnostic system of claim 1, wherein the contact being electricallycoupled between the battery module and an electrical load, the high sidedriver circuit being electrically coupled to a high side end of thecontactor coil, the low side driver circuit being electrically coupledto a low side end of the contactor coil.
 11. The diagnostic system ofclaim 1, wherein the vehicle electrical system further includes firstand second voltage regulators, the first voltage regulator outputting afirst voltage, the second voltage regulator outputting a second voltage,the diagnostic system further comprising: a first voltage dividercircuit outputting a third voltage in response to the first voltagewhich is less than the first voltage; a second voltage divider circuitoutputting a fourth voltage in response to the second voltage which isless than the second voltage, the fourth voltage being greater than thethird voltage; the first analog multiplexer having a third input port,the third input port of the first analog multiplexer receiving the thirdvoltage from the first voltage divider circuit; the second analogmultiplexer having a fourth input port receiving the fourth voltage fromthe second voltage divider circuit; the analog-to-digital converterreceiving the third voltage from the output port of the first analogmultiplexer and the fourth voltage from the output port of the secondanalog multiplexer at third and fourth times, respectively, andoutputting a first voltage value and a second voltage value,respectively, based on the third voltage and the fourth voltage,respectively, that are received by the microcontroller; themicrocontroller determining a first ratio value based on the first andsecond voltage values; and the microcontroller commanding the high sidedriver circuit and the low side driver circuit to transition the contactof the contactor to the open operational position when the first ratiovalue is outside of a predetermined ratio range indicating that at leastone of the first and second analog multiplexers are malfunctioning. 12.The diagnostic system of claim 11, wherein the microcontrollerdetermines the first ratio value utilizing the following equation: firstratio value=first voltage value/second voltage value.
 13. The diagnosticsystem of claim 12, wherein the predetermined ratio range has an upperthreshold ratio and a lower threshold ratio, and when the first ratiovalue is less than the lower threshold ratio then the microcontrollerdetermines that the second analog multiplexer is malfunctioning, andwhen the first ratio is greater than the upper threshold ratio then themicrocontroller determines that the first analog multiplexer ismalfunctioning.